Farming is the oldest wealth-creating business known to man. Current scientific strategies to maintain and improve yields in support of high-input agriculture place great emphasis on ‘fail-safe’ techniques for each component of the production sequence with little consideration of the integration of these components in a holistic, systems approach. Research for sustainable agricultural practices requires a far greater emphasis on such an approach than now is fashionable, despite all the rhetoric given politically to sustainability.
The populations of the world's poorest countries have been growing rapidly, increasing the demand for food. At the same time environmental degradation—both natural and man made—has reduced the ability of farmers to grow food in many areas. A lot has been written about the significant contribution due to “Green Revolution” and correctly so, especially considering our failure to control unsustainable population growth. Hardly any one argues that modern agriculture is sustainable. Besides, high input agriculture is increasingly recognized as an environment degrading and not profitable. We now recognize that technical progress may have social and environmental costs we cannot pay. People are now seriously concerned with the protection of the environment and even more about safeguarding their health. As now people realize that by consuming the standard agriculture based food products they are constantly taking in small quantities of poison of various kinds and much of this comes from the chemical pesticides that are used to produce food crops.
Modern farming requires large inputs of chemical fertilizer and stimulants to increase yields from hybrids. However for poor rural marginal farmers the use of chemical fertilizers and pesticides have made agriculture very expensive and to maintain yields in deteriorating soils increasing doses of modern chemical inputs have had to be used. The time has now come to consider alternative means of sustaining our agriculture and to protect the farmer from low prices, high indebtedness and to ensure that production incentives remain. For small farmers, organic farming is most suitable as considerable vertical integration is possible and appreciable cost savings could be achieved through the recycling of waste and other materials that are available within the system.
A considerable amount of literature is available on the practice of organic farming. Where organic farming is practiced, the farmer will use natural processes to enhance productivity, maintain the nutritive status of the soil to be less dependent on external resources and to keep his costs down. This will strengthen his social and financial position in the society. Organic farming uses natural materials which are the by products of the farm and are environmentally safe, it enhances the nutritive qualities of the soil and it nurtures the organisms in the soils, which are generally destroyed by the use of chemical manures and pesticides, and significantly reduces cost. Therefore, at this juncture further work on the development of agricultural biotechnology products based on natural products offers immense potential as viable alternative for sustainable agriculture.
Plants have remained central to every civilization as the primary source of life, due to their numerous applications in daily life. Plants are composed of chemical substances of which some are not directly beneficial for the growth and development of the organism. These secondary compounds have usually been regarded as a part of the plants' defense against plant-feeding insects and other herbivores. The pesticidal properties of many plants have been known for a long time and natural pesticides based on plant extracts such as rotenone, nicotine and pyrethrum have been commonly used in pest control.
Disease caused by various microorganisms such as fungi, bacteria, and viruses not only damage the plant as a whole but also severely affect quality of the crop. A number of physiological and biochemical alterations in the plants have been reported due to infection by fungi, bacteria, and viruses.
Improving soil fertility is one of the most common tactics to increase agricultural and forest production. Soil organisms, especially bacteria have a key role in determining the rate of organic matter decomposition and thereby nutrient mineralization. These processes determine the rate of nutrient supply to primary producers, largely determining the rate of biomass production and other fundamental ecosystem processes like interactions among different functional groups of organisms that constitute ecosystems. Therefore, elucidation of the mechanisms that determine species composition in plant communities is important. Rhizobacteria, once considered passive bystanders of the root environment, are now known to affect plant health, development, and environmental adaptation, both beneficially and detrimentally, and the importance of these bacteria in agriculture is expected to grow. A variety of mechanisms have been identified as being responsible for such plant growth promoting activity. For example, certain microorganisms indirectly promote plant growth by inhibiting the growth of deleterious microorganisms; or directly enhance plant growth by producing growth hormones; and/or by assisting in the uptake of nutrients by the crops, e.g., phosphorus.
Over the years, the demand for agricultural fruits, vegetables, and crops such as banana, mango, sweetpotato, cassava, and yam in the world market increased due to rising population and the influx of more novel applications in the food industry. Meanwhile, environment-friendly sustainable agricultural practices are getting more attractive to farmers since they have more benefits in doing such than the usual chemical control. The use of chemical agents for pests and diseases is disadvantageous because of high power consumption, soil and environment pollution, and the presence of pesticide residues, which are usually harsh chemicals, in fruits, vegetables, and crops harmful to humans and animals. The discovery of natural products that are beneficial to agriculture is highly important in addressing the concerns of farmers such as in increasing fruit, vegetable, and root crop yield and productivity.
Plant pests are a major factor in the loss of the world's commercially important agricultural crops resulting both in economic hardship to farmers and nutritional deprivation for local populations in many parts of the world. Broad spectrum chemical pesticides have been used extensively to control or eradicate pests of agricultural importance. There is, however, substantial interest in developing effective altenative pesticides.
Control of various pests through the use of biological molecules has been possible in only a limited number of cases. The best known examples of biological molecules with pesticidal uses are the δ-endotoxins from Bacillus thuringiensis (Bt), which is a gram-positive spore forming microorganism. Varieties of Bt are known that produce more than 25 different but related δ-endotoxins. Bt strains produce δ-endotoxins during sporulation the use of which is limited because they are active against only a very few of the many insect pests.
The limited specificity of the Bt endotoxins is dependent, at least in part, on both the activation of the toxin in the insect gut and its ability to bind to specific receptors present on the insects midgut epithelial cells. Therefore, the ability to control a specific insect pest using δ-endotoxins at present depends on the ability to bind an appropriate δ-endotoxin with the desired range of activity. In many cases, no such δ-endotoxin is known, and it is not certain that one even exists.
Plants also routinely become infected by viruses, fungi and bacteria, and many microbial species have evolved to utilize the different niches provided by the growing plant. In addition to infection by fungi and bacteria, many plant diseases are caused by nematodes which are soil-borne and infect roots, typically causing serious damage when the same crop species is cultivated for successive years on the same area of ground.
The severity of the destructive process of disease depends on the aggressiveness of the phytopathogen and the response of the host, and one aim of most plant breeding programs is to increase the resistance of host plants to disease. Novel gene sources and combinations developed for resistance to disease have typically only had a limited period of successful use in many crop-pathogen systems due to the rapid evolution of phytopathogens to overcome resistance genes.
It is apparent, therefore, that scientists must constantly be in search of new methods with which to protect crops against plant pests. It has been found in the present invention a novel class of fermented products which can be used to control plant pests.
Programmed cell death is a process whereby developmental or environmental stimuli activate a genetic program that culminate in the death of the cell. This genetic potential exists in most, if not all, multicellular organisms. In the case of invertebrates, programmed cell death appears to play a dual role by being an integral part of both the insect development process and a response mechanism to infections particularly of viral nature. Programmed cell death appears to be executed in several different manners leading to either apoptosis, atrophy or differentiation. Apoptosis is one of the best characterized types of programmed cell death encompassing cytological changes including membrane-bound apoptotic bodies and cytoplasmic blebbing as well as molecular changes such as endonucleolysis typified by the generation of oligosomal length fragments. Although the overall apoptotic phenomenology is rather conserved among the different organisms, it is interesting to point out that, for many insect cells, cytoplasmic vacuolization and swelling rather than condensation seem to be the cytological features associated with apoptotic processes. The novel class of products disclosed within the present invention may also induce programmed cell death and exert a pesticidal effect.
Additionally, since crop yield decreases by as much as 30% to 100% in case of cultivating crops without pesticides, it is essential to use the pesticides for improving crop yield. However, improper use of synthetic chemical pesticides in crop production causes several problems such as nonselective toxicity, accumulation of toxic compounds and outbreak of pathogens resistant to the pesticides. One way to handle these problems is to develop biopesticides using fermented products incorporating certain microorganisms. Biopesticides are roughly classified into plant extracts, microorganisms, natural enemies, natural bioactive substances, fermentation products of certain plant materials and genetically modified organisms (GMO). Bio-pesticides can be safer, more biodegradable, and less expensive to develop than synthetic chemical pesticides.
The study on the development of biopesticides, especially microbial fungicides, has been a major interest in the field of plant pathology, and there is active interest in development of more effective products for different crops.
Plants are exposed to many microbes, including bacteria, viruses, fungi, and nematodes. Although many of the interactions between these microbes and plants are beneficial or innocuous, many of the interactions are harmful to the plants. Diseases of agricultural crops, ornamental plants, forests, and other plants caused by such plant pathogens, particularly bacterial pathogens, are a worldwide problem with enormous economic impact.
There are many pathogenic species of bacteria, fungi, and nematodes. Diseases caused by fungal species include pre- and post-emergence seedling damping off, hypocotyl rots, root rots, crown rots, and the like. Pathogenic nematodes cause diseases such as root galls, root rot, stunting, and various other rots. Some nematodes also function as vectors of plant viruses.
Bacterial pathogens have a significant impact on worldwide agriculture. Such plant pathogenic bacteria include species of Pseudomonas, Erwinia, Agrobacterium, Xanthomonas, and Clavibacter. Pseudomonas and Xanthomonas species affect a large number of different crops. For example, Pseudomonas syringae causes bacterial speck of tomato; Xanthomonas campestris pv. malvacearum causes angular leaf spot of cotton; Pseudomonas solanacearum causes bacterial wilt of potato; and Pseudomonas tolaasii causes brown blotch disease of cultivated mushrooms. Potatoes and many other crops, such as celery, head lettuce, carrot, Japanese radish, wasabi, tobacco, tomato, cyclamen, Chinese cabbage, and cabbage, are susceptible to the so-called bacterial soft rots.
Erwinia carotovora is a soft rot bacterium that softens and rots storage tissues of many plants and is reported to be ubiquitous in soil. The bacterium typically enters plant tissues through injuries caused by insects, wind, tools, and the like. The bacterium invades the site of injury, and if temperature and moisture conditions are suitable, the bacteria rapidly multiply and macerate the tissue. For example, Erwinia bacteria are latent in potato plants, and will preferentially attack the stem and the tubers only after wounding. Potato seed pieces are also susceptible to infection through the cut surfaces. Erwinia carotovora has a substantial impact on the potato industry.
Agricultural production of major crops has always been impeded by plant pathogens. Diseases caused by plant pathogens often limit the growth of certain crops to certain geographic locations and can destroy entire crops. Crop losses resulting from the deleterious effects of plant pathogens are, thus, a serious worldwide agricultural problem, particularly since there are no known treatments for many of the diseases caused by plant pathogens. Even in instances where agrichemicals and pesticides are effective against plant pathogens, their use is increasingly under attack because of injurious effects on the environment and human health.
Because pesticides are often ineffective, unavailable, and/or environmentally unacceptable, there is a need to develop alternative means for effectively eradicating or reducing the harmful effects of plant pathogens. In recent years, much research has focused on the development of means for biocontrol of such pathogens and on the development of pathogen-resistant plants by breeding or by genetic engineering. There are few examples, however, of successful production of effective biocontrol methods or disease-resistant plants.
Application of antibiotics, such as streptomycin, and metal compounds, such as copper-containing Bordeaux mixture, has been the conventional method of control for many bacterial diseases. For example, Pseudomonas syringae pv. tomato, which causes bacterial speck of tomato, is presently controlled by frequent application of copper-containing sprays, which, in addition to their unfavorable environmental impact, select for copper-resistant strains. Treatment of apple and pear orchards with streptomycin to control the fireblight pathogen, Erwinia amylovora, has resulted in the appearance of streptomycin-resistant strains. Xanthomonas campestris pv. malvacearum, which causes angular leaf spot of cotton, presently is controlled by treating seeds with mercury-containing compounds and copper sprays. Other Xanthomonas campestris species, such as X. campestris pv. vesicatoria and X. campestris pv. campestris, can be seedborne, and there are no effective means for treating the seeds without injury thereto. These chemicals give unsatisfactory control, however, and also kill useful bacteria, contaminate the environment, and cause chemical injuries. Antibiotic-resistant bacteria have also appeared, and the ability of bacteria to transfer multiple drug resistance genes between genera potentially threatens antibiotic treatment of diseases of humans and/or animals.
Since there are few means for controlling plant bacterial pathogens, and those that are available, such as the heavy metal-containing sprays and antibiotics, are not highly effective and are environmentally unacceptable, and since there are relatively few bacterial pathogen-resistant vegetable or fruit plants available, there is a need for the development of effective, non-toxic, biodegradable and environmentally acceptable means for the control of plant pathogens. There is also a need to develop means for treating plants to eradicate or control plant diseases of numerous origins.
Additionally, the biological treatment or bioremediation of waste water, soil, oil spills, refinery waste, refinery and waste water treatment sludge contaminated with hydrocarbonaceous contaminants, and the like, is desirable. These processes depend on natural bacteria or fungi to biodegrade the typically hydrocarbon hydrocarbonaceous contaminants, into more environmentally friendly materials (bioremediation) and include, in addition to the well known aerobic and/or anaerobic processes for waste water treatment, processes used for the treatment of oil spills on water, land and the other contaminated substrates mentioned above. Cellulosic and lignin containing materials, along with bacteria and, if needed, nitrogen and phosphorous bacteria nutrients, are often used in the bioremediation of soil and other particulate solid or semi-solid substrates, such as sludges. Oil spills, especially on water, are particularly troublesome to treat, as are oil producing well sites contaminated with crude oil. Waste water processes, in addition to producing bioremediated wastewater, also produce contaminated sludge. This sludge must also be treated, to biodegrade the hydro carbonaceous contaminants remaining in it. One or more cellulosic materials, such as wood chips and straw, are typically added to the sludge, as what is referred to as an amendment material, and mixed therewith to provide porosity and sites for the bioactive bacteria When treating land contaminated with hydro carbonaceous material, such materials are mixed in with the land or soil, to form a composted mass in which the hydrocarbons biodegrade into carbon dioxide and water.
There is also a strong environmental and economic demand for accelerated activity bacteria capable of breaking down unwanted solids suspended or partially dissolved in aqueous media. Such solids have been classified in several ways including: total suspended solids (TSS), total volatile solids (TVS), sludge, and collectively, fats, oils and greases (FOG). Such solids have also been classified in their ability to enhance the life-bearing capabilities of the liquid in which they are suspended. Normal classifications include chemical oxygen demand (COD) and biological oxygen demand (BOD). Accelerated activity bacteria (i.e. highly active bacteria) have also been used to breakdown certain toxic wastes such as phenolic compounds and chromium by-products.
In a typical application, active bacteria, after acclimation, are used to treat toxic wastes to produce harmless, easily disposed non-toxic end products. Highly active bacteria have also been used to control or eliminate malodorous aqueous effluents. Malodorous substances such as hydrogen sulfide, ammonia or butyric acid, if broken down or denatured, are essentially odorless. An example of a material which falls in both the classifications of toxic material and malodorous material is hydrogen sulfide which, in its gaseous form or an aqueous solution is both toxic and malodorous.
Several strains of bacteria, normally found in soil, have been found to significantly shorten the breakdown cycle of solid wastes generally found in sewage. Examples of such soil bacteria include the genera of Arthrobacter, Bacillus, Pseudomonas, Flavobacterium and Acinetobacter, to mention a few. Certain bacteria found in animal intestines have been found to produce enzymes which, in turn, preferrably breakdown fats, oils and greases. Examples of such enzymes are found in many ruminant animals. Especially of note are the lipase producers found in sheep. Lastly, bacteria including varieties of Rhodospirillum and Chromatium are commonly found in salt water and have been found to rapidly and efficiently breakdown aqueous solutions of hydrogen sulfide. These are but a few examples of the many circumstances in which bacteria found in one environment can be usefully employed to remove unwanted species and solutes in other environments.
There is also a need for a bioremediation process in contaminated areas, such as crude oil production sites, that will provide reasonably rapid biodegradation of the contaminant, with minimal effect on soil reuse (e.g., minimal or no reduction in compressive strength or load bearing capacity). Additionally, since large amounts of organic waste are generated annually from agricultural plantations, animal farms, mills, food processing plants and industrial plants there is a need to find ways to dispose of these wastes in an environmentally friendly way.
There is a long felt need to provide environmentally acceptable compositions and methods that provide soltuions of all the aforementioned problems.